The present invention relates to a tool for rotary, cutting machining, including a tool body, a cutting portion and means for fastening. The tool body has a front surface and the cutting portion has a support surface provided to dismountably abut against each other, substantially in a radial plane. The invention also relates to a separate tool tip, a cutting portion, a tool body as well as to a method for manufacturing a tool tip or a cutting portion.
It is previously known to use interchangeable cutting edges on different types of tools for cutting machining. This technique has however its practical limitation because of strength reasons when it comes to milling- and drilling tools rotating around its longitudinal axis.
Through U.S. Pat. No. 4,684,298 is previously known a drill with a dismountable cutting portion secured in a drill body by two screws, which are provided opposite sides of a central line of the drill. In the known drill, screws transfer torsion which is created during drilling, to the drill body. Such a drill suffers from a number of drawbacks, partly that it becomes statically unstable, which is solved by positioning resilient sleeves around the screws, and partly that the cutting portion is forced to contain less amount of cemented carbide (since the screws need space) whereby the propensity for crack formation increases. In addition the screws are submitted to shear forces and exchange of the cutting portion becomes troublesome.
Furthermore, it is previously known through European Document 0 358 901 to provide a drill with a dismountable cutting portion secured in a drill body by means of at least one screw, which is eccentrically positioned relative to the rotational axis of the drill. The cutting portion carries two indexable cutting inserts, and a pilot drill extends centrally therethrough. This known drill has the same drawbacks as mentioned above.